Process for preparing an iron oxide

Abstract

A process is disclosed for the production of micaceous iron oxide using metallic iron, for example scrap iron, as a feed stock for the preparation of an iron chloride and the resulting iron chloride is oxidized at an elevated temperature in the presence of a salt of an alkali metal or alkaline earth metal, preferably sodium chloride. A reaction may be effected in a packed tower reactor comprising a refractory tube 7 containing an inert packing material e.g. aluminosilcate ceramic balls. The reaction charge including packing material, metallic iron and the salt is introduced via hopper 13. A tube 7 is externally heated by electrical resistance elements 10 and chlorine and an oxidizing gas are introduced at inlet 8 and the off-gas removed at outlet 9. The micaceous iron reaction product is obtained as a coating on the inert packing material. Micaceous iron oxide is used as a pigment for the formulation of metal protective paints.

We claim: 
     
       1. In the process for the preparation of micaceous iron oxide comprising combining an iron chloride with at least one salt of an alkali metal or alkaline earth metal at sufficiently elevated temperatures to form a molten phase, and subjecting the resultant molten phase to oxidation with oxygen or oxygen-containing gas, the improvement which comprises carrying out the oxidation reaction on a solid surface such that the molten phase is distributed as a melt film on the solid surface, the melt film having a minimum thickness of 150 microns and the micaceous iron oxide being formed in the melt film. 
     
     
       2. In the process for the preparation of micaceous iron oxide comprising combining an iron chloride with at least one salt of an alkali metal or alkaline earth metal at sufficiently elevated temperatures to form a molten phase, and subjecting the resultant molten phase to oxidation with oxygen or oxygen-containing gas, the improvement which comprises carrying out the oxidation reaction in the presence of an inert, particulate, packing material, such that the molten phase is distributed as a melt film on the solid external surface of the packing material, the melt film having a minimum thickness of 150 microns and the micaceous iron oxide being formed in the melt film. 
     
     
       3. A process according to claim 2, wherein the reactions are effected at a temperature of about 650° to 850° C. 
     
     
       4. A process according to claim 2, wherein the salt:iron weight ratio is within the range of about 0.25:1 to 10:1. 
     
     
       5. A process according to claim 2, wherein the salt is selected from the group consisting of chlorides, bromides, iodides and sulphates of alkali metals and alkaline earth metals. 
     
     
       6. A process according to claim 5, wherein the salt is sodium chloride. 
     
     
       7. A process according to claim 2, wherein the weight ratio of inert material to iron content (expressed as metallic iron) is about 4:1 to 20:1. 
     
     
       8. In the process of claim 2, wherein the packing material comprises ceramic spheres. 
     
     
       9. The process of claim 8, wherein the spheres have a diameter of about 12 millimeters.